Photographic reproduction process and apparatus therefor



Sept. 4, 1962 s. LEVINOS 3,052,541

PHOTOGRAPHIC REPRODUCTION PROCESS AND APPARATUS THEREFOR Filed Jan. 14,1959 INVENTOR STEVEN LEVINOS MW Bymgm ATTORNEY United This inventionrelates to photographic reproduction and, more particularly, to aself-stabilizing reproduction process and apparatus therefor.

It has long been known that a finely divided suspension of zinc oxide inthe presence of a small quantity of silver nitrate darkens when exposedto white light. The reaction is presumed to be The present invention hasfor its primary object to make practical use of the above phenomenon andprovides a print-out photographic process utilizing a copy materialwhich is insensitive to light until activated by a suitable agent.

It is a particular feature of the invention that by virtue of theprocess and simple apparatus for its application, photographic materialmay be manufactured and distributed which is insensitive to light andmay be stored without deterioration for an unlimited time.

It is a further object of the invention to provide a simple apparatuswhich utilizes the above type of material and will make print-out copiesof any translucent original, particularly for line copy or continuoustone photographs.

Other objects and features will be apparent from the followingdescription of the invention, pointed out in particularity in theappended claims, and taken in connection with the accompanying drawingin which:

FIG. 1 is a simplified schematic representation of a photographicreproduction apparatus suitable for employing a roll oflight-insensitive copy material.

I have found that a thin coating of zinc oxide on a suitable support, incombination with various silver compounds, can be used as aself-stabilizing reproduction system for line copy or continuous tonephotographs. This is a negative-positive system which may be used forcontact printing of negatives or for enlarging by proec tion, e.g., frommicrofilm. In its elementary form, the zinc oxide and silver compoundmay be combined and the support coated with this composition. This isrelatively insensitive to light, but when moistened with water, itbecomes light-sensitive and can be so used. However, while such acoating in a dry state is relatively insensitive to light, it will,nevertheless, discolor in storage. This is presumed to be due to agradual conversion of the silver compound to the oxide by virtue of thepH of the system (an aqueous slurry of zinc oxide has a pH in the rangeof 7.0-7.3). Therefore, in accordance with the invention, I propose theuse of a copy material which is photochemically inert, such as a coatingof zinc oxide or titanium dioxide in an appropriate binder, and activatethis material prior to its use by means of an aqueous activating agentcontaining a silver compound. This can be accomplished in the followingmanner.

A coating of zinc oxide with an appropriate binder, such as gelatin, isfirst made on a suitable support. This may or may not contain asensitizing dye. Such a coating can be made in the presence of light andmay be stored in light indefinitely without adverse effects. Thiscoating can then be sensitized in the printer immediately prior toexposure by moistening it with an aqueous solution of a silver compound.The latter may contain a Patent "ice wetting agent and may or may notcontain a sensitizing dye as desired.

The activating solution may be any aqueous solution of a soluble silversalt. Illustrative of such silver salts operable to obtain a print-outimage upon exposure are silver acetate, silver benzoate, silverfluoride, silver lactate, silver nitrate, silver nitrite, silverphenolsulfonate,

silver picrate, silver selenate, silver selenite, silver sulfate,

silver sulfite and silver thiosulfate.

With reference to the earlier observation hereinabove mentioned, it isnoted that active or nascent oxygen is evolved as one of the reactionproducts. It is proposed that this reaction may be accelerated by therapid removal of the evolved oxygen. This may be accomplished either byselecting for the activating agent a silver compound which can befurther oxidized, e.g., silver nitrite or silver sulfite, or adding asmall amount of zinc sulfite or zinc nitrite to the zinc oxide coatingcomposition.

If silver nitrite, silver sulfite or silver selenite are used, thereactions would be as follows:

(1) Light ZAgNOz ZnO 2Ag Z11(NO2)2 %O: (2) Z11(N0z)2 20 Z11(NOSimilarly: (1) Light AggSO; ZnO 2Ag ZIlSOz V 0: (2) ZDSO3 0 ZI1S0| and(1) Light gt Oa ZnO 2Ag ZnSeOz (2) ZnSeO O ZnSeO As an alternative,certain oxidizable organic compounds, such as sodium form'ate, may beadded to the zinc oxide coating.

The apparatus for the production of enlargements or contact prints mayhave various forms. It is essential, however, that the embodimentcontain means for activating the copy material by applying an aqueoussolution of silver compound. In a schematic form, as shown in thedrawing, the apparatus consists of a base 10 on which is mounted alight-tight enclosure 12. This may be of a simple rectangularcross-section, resting on legs 14 and 15. An entrance opening 16 in theside 17 of the enclosure may be in the form of a slit lined with anysuitable padding for light-tightness, such as a velvet liner 18, throughwhich the light-insensitive copy material may enter. Although thematerial is photochemically inert until activated, the enclosure 12 mustbe lighttight inasmuch as the material will become actinically reactivetherewithin.

The coated material may be in the form of a roll 20 held on a spooljournalled in frame member 22 afixed to the support 10. A roller 24mounted on bracket 25 aflixed to the side 17 is arranged to guide thematerial through the entrance opening 16. Inside the enclosure 12 andnear the entrance opening 16 is a tank 28 which is mounted on a platform29 supported on a rack 31 extending from the bottom 30 of the enclosure12.

A pinion 34 journalled in frame 35 engages the rack 31 and may beactuated by the handle 37 so as to lower or raise the tank 28. Withinthe latter are wetting rollers 39 and 40 rotatably arranged in suitableframes 41 and 42, respectively, attached to the bottom of the tank 28. Aguide roller 44 is mounted on the inner top side of the enclosure by asuitable bracket 48 extending downwardly between rollers 39 and 40.

In close proximity to the tank 28 is located the exposure areaconsisting of a platen 50 which is resiliently held by the springs 51and 52 and secured to suitable mounting brackets 53 and 54,respectively. Guide rollers 61 and 62 are placed alongside the platenand mounted in suitable frames which may be secured to the side walls ofthe enclosure. A frame member 63 in contact with the platen 50 mayprovide space for a negative -for contact printing or, as shown here byway of example, has an exposure opening to permit the projection of animage onto the copy material by means of a projector 65. A slit 66 ofthe projector 65 accommodates the translucent material of which anenlargement is desired. The projector 65 is merely schematicallyindicated and may be of any suitable type, including a light source, notshown here.

Adjacent the roller 62 is a heating element 68 placed in a parabolicreflector 69 for the purpose to be de scribed in connection with theoperation of the device.

The exit opening 70 in the side 71 of the enclosure 12 is located nearthe heating element 68 and is similar in construction to the entranceopening 16.

A roller 72 mounted in a bracket 73 afiixed to side Wall 71 guides thematerial onto the Windup roller 75. The latter is mounted on a framemember 76 attached to the support 10. A handle 78 is provided for windupof the exposed copy material.

The operation of the reproduction apparatus is as follows. As outlinedabove, the copy material used consists of a support, such as paperorfilm if a transparency is desired, coated with zinc oxide in a suitablebinder, such as gelatin. The roll is placed onto the spool frame 22 andthe material threaded through the entrance opening 16 under roller 44and over rollers 61, 62 and 72 onto the windup spool 75. The tank 28 isnormally in the dovm position so that the wetting rollers 39 and 40 donot touch the material until it is desired to activate it for the makingof copies. To do so, the tank 28 is raised by the lever 37 so that thematerial firmly contacts the rollers 39 and 40 by virtue of theintermediate roller 44. The handle 78 of the windup spool 75 is turned,whereby the material riding over rollers 39 and 40 is activated by beingmoistened with the aqueous silver compound. A sufficient length ofmaterial is thus moved past the wetting rollers to enter between theplaten 50 where it is held flat, ready for exposure. Upon exposure bymeans of the projector 65, the handle 78 is turned again so that theexposed portion of the material passes over roller 62 and past theheating element 68 where the material is dried.

it is characteristic of this material that in a dry state it isphotochemically inert. Therefore, after exposure, the fixing of theimage requires only heat so as to evaporate water from the moistsurface. The heating element 68 and reflector 69 serve this purpose.

The advantage of rapid drying is to increase the reaction in that theprint-out image, which is usually dark, will absorb heat rays, whereasthe unexposed or white 4 areas reflect heat rays. Consequently, adifferential heating is produced. As the temperature of the imageincreases, the reaction can be expected to proceed at an acceleratedrate.

I claim:

1. A process of photographic reproduction utilizing a copy materialconsisting of a support having a coating comprising a photographicallyinert amphoteric metal oxide selected from the group consisting oftitanium dioxide and zinc oxide which comprises placing said material,prior to sensitization and exposure, in a light-tight enclosure andapplying as the sole activating agent to said coating an aqueoussolution of a Water-soluble silver salt which, in contact with saidamphoten'c metal oxide, forms an actinic reaction product, exposing saidactivated coating while in a moist state to light through a translucentoriginal to be reproduced, thereby producing a print-out image andfixing the image by evaporating water from the moist surface, thusrendering said coating photographically insensitive to light prior toleaving said enclosure.

2. A process in accordance with claim 1 wherein said photographioallyinert metal oxide is Zinc oxide.

3. A process in accordance with claim 1 wherein said coating comprises amixture of zinc oxide and zinc sulfite.

4. A process in accordance with claim 1 wherein said coating comprises amixture of zinc oxide and zinc nitrite.

5. A process in accordance with claim 1 wherein said coating comprises amixture of zinc oxide and an oxidizab'le compound selected from thegroup consisting of sodium formate and sodium oxalate.

6. A process in accordance with claim 1 wherein said activating agentconsists essentially of an aqueous solution of silver nitrite.

7. A process in accordance with claim 1 wherein said activating agentconsists essentially of a solution of silver sulfite.

8. A process in accordance with claim 1 wherein said activating agentconsists essentially of a solution of silver selenite.

9. A process in accordance with claim 1 wherein said silver salt issilver nitrate.

10. A process in accordance with claim 1 wherein the rendering of saidcoating photographically inert afiter exposure consists of evaporatingthe water by the application of heat.

References Cited in the file of this patent UNITED STATES PATENTS TatumMay 13, 1865 Mees Aug. 5, 1924 OTHER REFERENCES

1. A PROCESS OF PHOTOGRAPHIC REPRODUCTION UTILIZING A COMPRISING A PHOTOGRAPHICALLY INERT AMPHOTERIC METAL COMPRISING A PHOTOGRAPHICALLY INERT AMPHOTERIC METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF TITANIUM DIOXIDE AND ZINC OXIDE WHICH COMPRISES PLACING SAID MATERIAL, PRIOR TO SENSITIZATION AND EXPOSURE, IN A LIGHT-TIGHT ENCLOSURE AND APPLYING AS THE SOLE ACTIVATING AGENT TO SAID COATING AN AQUEOUS SOLUTION OF A WATER-SOLUBLE SILVER SALT AN ACTINIC REACTION PRODUCT, EXPOSING SAID ACTIVATED COATING WHILE IN A MOIST STATE TO LIGHT THROUG HA TRANSLUCENT ORIGINAL TO BE REPRODUCED, THEREBY PRODUCING A PRINT-OUT IMAGE AND FIXING THE IMAGE BY EVAPORATING WATER FROM THE MOIST SURFACE, THUS RENDERING SAID COATING PHOTOGRAPHICALLY INSENSITIVE TO LIGHT PRIOR TO LEAVING SAID ENGRAPHICALLY INSENSITIVE TO LIGHT PRIOR TO LEAVIGN SAID EN
 5. A PROCESS IN ACCORDANCE WITH CLAIM 1 WHEREIN SAID COATING COMPRISES A MIXTURE OF ZINC OXIDE AND AN OXIDIZABLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF SODIUM FORMATE AND SODIUM OXALATE. 